Fast Algorithm for Simulation of Signals in Medical Ultrasound Blood Flow Imaging
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The commonly used simulation method Field II, which is based on the spatial impulse response approach, has excellent accuracy in linear domain. However the computational time can be up to many days for one simulation. One of the solutions to this problem is a convolution-based methodology called COLE. It is much faster than Field II and has very good approximation. It generates the data by reducing multi-dimensional convolution model to multiple single-dimensional convolutions. This thesis is about implementing COLE on the FieldSim 3 platform and using it for blood flow imaging. This platform is written in MATLAB with object-oriented programming and it is now under development at department of circulation and medical imaging. Both Field II and real scanner have been used to compare with COLE. The simulated phantom for both simulators was a straight tube with scatterers moving inside, whereas a string phantom was used to get the data from the scanner. The computational time of COLE with 2D Doppler mode scan in FieldSim 3 achieved 85 times faster than Field II. The plotted PW Doppler spectra and the 2D power spectra showed that the velocity resolutions of both simulators were at the same level. COLE had higher noise floor than Field II and scanner in Doppler mode scan. COLE had relatively high sampling frequency requirement compared with Field II. If the sampling frequency was not high enough, COLE would produce side lobes in the PW Doppler spectra.